Apparatus and method for manufacturing a multi-layer web product

ABSTRACT

An apparatus and method for manufacturing a multi-layer web product. A long fiber stream is directed around a rotating carding cylinder. Two combing cylinders are disposed adjacent the carding cylinder to comb a first web of long fiber and a second web of long fiber, respectively, from the carding cylinder. A first conveyor receives the first web from the first combing cylinder and transports the first web toward a layering point. Similarly, a second conveyor receives the second web from the second combing cylinder and transports the second web toward the layering point. A short fiber deposition unit is disposed adjacent the second conveyor and deposits short fibers onto the second web. At the layering point, the first conveyor deposits the first web onto the second web, with the short fibers sandwiched therebetween, to form a layered web product.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. application Ser. No. 12/176,339,filed Jul. 19, 2008, which is a division of U.S. application Ser. No.10/984,085, filed Nov. 8, 2004, which is the Non-Provisional of U.S.Provisional Application Ser. No. 60/523,362, filed on Nov. 18, 2003. Thepriorities of the foregoing applications are hereby claimed and theentirety of their disclosures incorporated herein by reference.

FIELD OF THE INVENTION

The field of the present invention is the manufacture of multi-layer webproducts, particularly web products made from nonwoven fibers.

BACKGROUND

Consumers tend to prefer nonwoven web products made from long fibersbecause of their superior hand feel as compared to short fibers such aswood pulp. Unfortunately, long fiber web products are generally moreexpensive than short fiber web products. Therefore, in order to meet thedemands of consumers by providing a web product having a superior handfeel and meet the needs of manufacturers by reducing costs of materialsand production, web products that include a combination of long andshort fibers have been developed.

FIG. 1 schematically illustrates a prior art apparatus for manufacturingwet laid fibrous web products using in-line hydroentanglement. Thefibers are opened, treated, blended, diluted, and refined as necessaryat the pre-treatment stage 50 of the apparatus to form the furnish. Toprovide a product having a hand feel that is superior to short fiberproducts, the furnish is formed from a combination of short and longfibers mixed together (throughout this description of the background andthe description of the preferred embodiment of the invention, shortfibers are typically natural fibers, but may also be or includesynthetic fibers, while long fibers are typically synthetic fibers, butmay also be or include natural fibers). From the pretreatment stage 50,the furnish is directed into the head box 51, from which the fibers aredeposited as a web onto the forming wire 52. Once on the forming wire52, the web is conveyed to the hydroentanglement unit 53, which directshigh pressure water streams at the web to entangle the fibers. Dependingupon the final web properties desired, the web may be transported underthe hydroentanglement unit multiple times or under a hydroentanglementunit with multiple hydroentangling heads, or the web may be turned overto direct the high pressure water at the other side of the web.Following hydroentanglement, a drying unit 54 dries the web using anynumber of conventional drying processes, such as steam heated candryers, TAD (through air drying), or Radiant Heat (such as Infra-Red).After drying, the web is wound into a roll 55 for storage or subsequentprocessing.

The combination web products produced using the apparatus of FIG. 1exhibit cost savings over all long fiber products. At the same time,such products come closer to providing, but do not reach, the superiorhand feel associated with all long fiber products.

Two-layer web products have also been developed. Such web products havea first layer of short fibers and a second layer of long fibers. FIGS.2-4 schematically illustrate prior art apparatuses for manufacturingtwo-layer web products. The apparatus of FIG. 2 is employed tomanufacture a single layer wet laid short fiber web product. Such ashort fiber web product is used as the first layer of a two-layer webproduct in a downstream process. In brief, the short fibers areseparated, treated, blended, diluted and refined as necessary at thepre-treatment stage 60 of the apparatus to form the furnish. From thepre-treatment stage 60, the furnish is directed into the head box 61,from which the fibers are deposited onto the forming wire 62. A dryingunit 63 dries the web and the dried web is wound into a roll 64 pendingsubsequent processing.

The apparatus of FIG. 3 is employed to manufacture a single layer longfiber web product. Such a long fiber product is used as the second layerof a two-layer web product in a downstream process. The web formed withthis apparatus typically uses longer fibers (generally 25 to 45 mm, orlonger such as 45 to 100 mm). The long fibers are pre-opened in the baleopener 70 and transported to the fine opener 71. Once the fibers aresufficiently separated and declumped for final processing and forming,they are transported to the chute feed 72 which meters them at a uniformrate and volume onto the feed roll 73 and then the lickerin roll 74. Thelickerin roll 74 transfers fibers in a separated, uniform, andcontrolled manner to the main carding cylinder 75. The fibers arerepeatedly combed and stripped from the main carding cylinder 75 by theworker and stripper rolls 76. A combing cylinder 77 is positioned tocomb the web from the main carding cylinder 75 and transfer the web tothe doffer cylinder 78 (which also serves to comb the web). The web istransferred from the doffer cylinder 78 onto the forming wire 82. Onceon the forming wire 82, the web is passed under a hydroentanglement unit79 and through the drying unit 80. The dried web is wound into a roll 81pending subsequent processing.

The long fiber web product created by the process of FIG. 3 may besubstituted with a two-layer long fiber web product throughimplementation of the carding apparatus disclosed in European PatentApplication EP 1046731 A1, the disclosure of which is incorporatedherein by reference. With such a carding apparatus, two webs are combedfrom the main carding cylinder, recombined, and joined either throughentanglement or light adhesive bonding. Subsequent processing of bothone- and two-layer long fiber webs may be performed in the same manner.

The apparatus of FIG. 4 is employed to combine a short fiber web with along fiber web into a two-layer web product. A long fiber web, such asone made by the apparatus of FIG. 3, is unwound from a roll 81 onto acarrier wire 82. A short fiber web, such as one made by the apparatus ofFIG. 2, is unwound from a roll 64 and laid upon the long fiber web. Thetwo webs are passed under a hydroentanglement unit 90, through a dryerunit 92, and wound into a roll 93.

The two-layer web products produced using the apparatuses of FIGS. 2-4also exhibit cost savings over all long fiber products. However, becauseonly one side of such web products exhibits the superior hand feel oflong fibers, while the other side exhibits the less desired hand feel ofshort fibers, such a product does not meet with the same consumer demandas does an all long fiber web product.

FIGS. 2-4 illustrate an off-line process of manufacturing the two-layerweb product. In practice, however, the apparatuses of FIGS. 2-4 arecombinable for in-line formation of the two-layer web product.

U.S. Pat. No. 6,110,848, the disclosure of which is incorporated hereinby reference, teaches a three-layer web product and the productionthereof. This three-layer web product goes further toward meeting thedemands of consumers and the cost needs of manufacturers, as it includestwo outer layers of long fiber and a middle layer sandwichedtherebetween of short fiber. The apparatus of FIG. 5 is employed tomanufacture such a three-layer web product. A first long fiber web isunwound from a roll 81 onto a carrier wire 82. A short fiber web isunwound from a second roll 69 and laid upon of the first long fiber web.A second long fiber web is unwound from a roll 81 and laid upon theshort fiber web, thereby sandwiching the short fiber web between twolayers of long fiber. This three-layer structure conveyed under ahydroentanglement unit 90 and through a drying unit 92. As with otherprior art, hydroentanglement of the three-layer web may be done withmultiple passes, multiple heads, or on both sides of the web. The driedweb is wound into a roll 104 pending further processing.

The three-layer web product is superior to other prior art web productsthat combine long and short fibers because it has the superior hand feelon both sides of the product and the product may be bulked up with shortfiber as the middle layer without effecting the hand feel on either sideof the product.

The apparatus of FIG. 6 illustrates the process of FIG. 5 as an in-lineprocess. The long fiber forming equipment, labeled as C1 and C2,respectively, up to the doffer cylinder 78, is the same as described inconnection with FIG. 3. A first long fiber web from the first formingequipment C1 is laid upon the forming wire 125. Short fiber-depositionequipment S1 deposits short fiber upon the first long fiber web. Theshort fiber, whether from a roll or otherwise, is fed into a hammermill121 which separates the fibers. A transport fan 122 sends the separatedshort fibers to the forming heads 123, where the short fibers are blownonto the first long fiber web. Vacuum suction units 124 on the oppositeside of the forming wire 125 from the forming heads 123 assist informing the layer of short fibers on the first long fiber web. Thesecond long fiber web from the second forming equipment C2 is laid ontop of the short fibers. The three-layer structure is passed under thehydroentanglement unit 79, through the drying unit 80, and wound into aroll 105 pending subsequent processing.

Such an in-line process has the additional cost benefit of reducing oreliminating the need to store intermediary rolls. However, even withthese advances in the production of nonwoven web products where 1) theproducts better meet the demands of consumers and 2) the manufacturingcosts have been reduced, the costs of producing such web productsremains high and would significantly benefit from apparatuses andprocesses which serve to further reduce production costs.

SUMMARY OF THE INVENTION

The present invention is directed towards an apparatus and method formanufacturing a multi-layer web product. A carding cylinder is rotatedto transport long fiber. Two combing cylinders comb the long fiber fromthe carding cylinder to form first and second webs of long fiber. Bothwebs are deposited upon conveyors and conveyed toward a layering point.A short fiber deposition unit is disposed adjacent the conveyor carryingthe second web and deposits short fiber upon the second web. Theconveyor carrying the first web deposits the first web upon the secondweb at the layering point, thereby creating a layered web having outsidelayers formed of long fiber and an inner layer formed of short fiber.The layered web may thereafter be subjected to entanglement to betterbind the layers together.

Accordingly, the present invention provides an improved apparatus andmethod for manufacturing a multi-layer web product. Other objects andadvantages will appear hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, wherein like reference numerals refer to similarcomponents:

FIG. 1 schematically illustrates an apparatus and method formanufacturing wet laid hydroentangled web products in accordance withthe prior art;

FIG. 2 schematically illustrates an apparatus and method formanufacturing wet laid web products in accordance with the prior art;

FIG. 3 schematically illustrates an apparatus and method formanufacturing dry-laid web products in accordance with the prior art;

FIG. 4 schematically illustrates an off-line apparatus and method formanufacturing two-layer web products in accordance with the prior art;

FIG. 5 schematically illustrates an off-line apparatus and method formanufacturing three-layer web products in accordance with the prior art;

FIG. 6 schematically illustrates an in-line apparatus and method formanufacturing three-layer web products in accordance with the prior art;

FIG. 7 schematically illustrates an apparatus and method formanufacturing multi-layer web products in accordance with an embodimentof the present invention; and

FIG. 8 schematically illustrates an apparatus and method formanufacturing multi-layer web products in accordance with anotherembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Turning in detail to the drawings, FIGS. 1-6 illustrate the state of theprior art as previously described. In FIG. 7, long fibers are pre-openedin the bale opener 170 and transported to the fine opener 171. Once thefibers are sufficiently separated and declumped for final processing andforming, they are transported to the chute feed 172 which meters them ata uniform rate and volume onto the feed roll 173 and then the lickerinroll 174. The lickerin roll 174 transfers fibers in a separated,uniform, and controlled manner to the main carding cylinder 175. Thefibers are repeatedly combed and stripped from the main carding cylinder175 by the worker and stripper rolls 176. The number or worker andstripper rolls may vary as desired.

A first combing cylinder 177 a combs a first web from the main cardingcylinder 175. The first web is transferred to the first doffer cylinder178 a and from the first doffer cylinder onto the first conveyor 183 a.The first conveyor 183 a may be of any appropriate design known to thoseskilled in the art. The first conveyor 183 a transports the first web tothe layering point 196, which is the point at which the first and secondconveyors recombine the respective webs being transported.

At the same time the first web is combed from the main carding cylinder175, a second combing cylinder 177 b combs a second web from the maincarding cylinder 175. The second web is transferred to the second doffercylinder 178 b, and from the second doffer cylinder the web istransferred onto the second conveyor 183 b. As with the first conveyor183 a, the second conveyor 183 b may be of any appropriate design knownto those skilled in the art. The second conveyor 183 b transports thesecond web to the layering point 196. While the second web is on thesecond conveyor 183 b, but before the layering point 196, the second webpasses by the short fiber deposition unit 195, which deposits shortfibers upon the second web. This short fiber deposition unit may be ofthe design described in connection with FIG. 6, which separates shortfibers and uses air to lay the fibers evenly upon the second web, or itmay be of any other appropriate design known to those skilled in theart, such as depositing a web of short fiber upon the second web. It isworth noting again that the short fibers may be synthetic, but use ofnatural fibers as the short fibers generally makes the process moreeconomical. Similarly, the long fibers may be natural, but use ofsynthetic fibers as the long fibers generally makes the process moreeconomical.

At the layering point, a layered web is formed by depositing the firstweb upon the second web, the short fibers being sandwiched therebetween.The layered web is received by a third conveyor 184 which passes thelayered web under an entanglement unit 179 which directs jets of highpressure water at the web. The entanglement unit may be of any designknown to those skilled in the art, such as drum or flatbedhydroentanglers. Thereafter, the web is passed through a drying unit 180and wound into a roll 194 pending subsequent processing. However, ifdesired, subsequent processing may be performed in-line, therebynegating the need to wind the layered web into the roll.

In FIG. 8, three webs are combed from the main carding cylinder. Asbefore, the first combing cylinder 177 a combs and transfers the firstweb to the first conveyor 183 a via a first doffer cylinder 178 a. Thefirst conveyor 183 a transports the first web to the layering point 196.The second combing cylinder 177 b combs and transfers the second webonto a second conveyor 183 b via a second doffer cylinder 178 b, and thethird combing cylinder 177 c combs and transfers the third web onto thethird conveyor 183 c via a third doffer cylinder 178 c. The secondconveyor 183 b deposits the second web onto the third web before thethird web is transported under the short fiber deposition unit. Afterthe second web is deposited upon the third web, the combined second andthird webs pass under the short fiber deposition unit 195, whichdeposits short fibers upon the combined second and third webs. The firstweb is thereafter deposited upon the combined second and third webs atthe layering point 196, with the short fibers sandwiched therebetween.Hydroentanglement and drying proceed as previously described.

In general, it has been found that when more than one web is combed fromthe carding cylinder, thinner webs are produced which are more easilymanipulated to achieve desired properties of the web. Two generallydesired qualities of web products are a low ratio between the machinedirection strength and the cross direction strength of the web (“MD:CDratio”) and a consistent basis weight. Older carding apparatuses whichcombed only one web from the carding cylinder were often lucky toachieve a 10:1 MD:CD ratio. Some carding apparatuses have reduced theMD:CD ratio within the range of 5:1 to 3:1. Carding apparatuses, such asthe one depicted in FIG. 8 which comb three thinner webs from thecarding cylinder and which implement appropriate control features, arecapable of reducing the MD:CD ratio within the range of 3:1 to 1:1. Onesuch carding apparatus that has implemented control features to obtain alow MD:CD ratio is manufactured by F.O.R. of Biella, Italy, a divisionof FINCARDE S.p.H. Strade Campagne, also of Biella, Italy, as modelnumber 06803/D153C1. An additional important capability of the F.O.R.carding apparatus is that the webs combed from the carding cylinder tendto have an approximately uniform basis weight. Variation in the basisweight for each of three webs has been found to be minimal. The F.O.R.carding apparatus is thus capable of generating the different web layersin the most preferred manner, and may be modified to make the apparatusand perform the method of producing the multi-layer web product asdescribed herein.

A benefit of the present invention is the ability to reduce productioncosts by converting an older carding apparatus into a carding apparatusaccording to the present invention. Whereas prior to the presentinvention, multiple carding apparatuses and other equipment, such asthat previously described, were necessary to form a multi-layer webproduct, now a single carding apparatus may be adapted to comb two ormore webs from the carding cylinder, thereby enabling a multi-layer webproduct to be produced firm a single carding apparatus. Reducing theamount of equipment necessary to manufacture a multi-layer web productwill reduce the monetary and space requirements of manufacturingmulti-layer web products.

Another benefit of the present invention is that existing dry-form pulpmachines, which are losing utility within the industry as stand-aloneunits, may be retrofitted with a single carding apparatus of the typedescribed herein to produce web products that are desirable toconsumers. Investment costs for new equipment may thus be reduced whilethe useful life of existing equipment may be extended, thereby providingadditional cost benefits.

Thus, an apparatus and method for manufacturing multi-layer web productsare disclosed. While embodiments of this invention have been shown anddescribed, it will be apparent to those skilled in the art that manymore modifications are possible without departing from the inventiveconcepts herein. The invention, therefore, is not to be restrictedexcept in the spirit of the following claims.

1. An apparatus for manufacturing a multi-layer web product comprising: a carding cylinder adapted to rotate and transport long fiber, the carding cylinder including a plurality of combs disposed thereabout, the combs being adapted to comb long fiber from the carding cylinder; a first combing cylinder disposed adjacent the carding cylinder and adapted to comb a first web of long fiber from the carding cylinder; a first conveyor disposed adjacent the first combing cylinder and adapted to receive and transport the first web to a layering point, wherein the first combing cylinder and the first conveyor are adapted to maintain a ratio between a machine-direction strength and a cross-direction strength of the first web that is 3:1 or less and to maintain a basis weight of the first web that is approximately consistent throughout the first web; a second combing cylinder disposed adjacent the carding cylinder and adapted to comb a second web of long fiber from the carding cylinder; a second conveyor disposed adjacent the second combing cylinder and adapted to receive and transport the second web to the layering point, wherein the second combing cylinder and the second conveyor are adapted to maintain a ratio between a machine-direction strength and a cross-direction strength of the second web that is 3:1 or less and to maintain a basis weight of the second web that is approximately consistent throughout the second web; a short fiber deposition unit disposed adjacent the second conveyor and adapted to deposit short fibers onto the second web, wherein at the layering point the first conveyor is adapted to deposit the first web onto the second web, the short fibers being sandwiched therebetween, to form a layered web; a third conveyor adapted to receive the layered web; and a hydro-entanglement unit disposed adjacent the third conveyor and adapted to direct high pressure water at the layered web.
 2. The apparatus of claim 1, wherein the short fibers are in the form of a paper web. 